1. Technical Field
The present invention relates to a polarizing device, a method for manufacturing thereof, as well as a liquid crystal device and a projection display device.
2. Related Art
Polarizing devices formed including grid patterns that are shaped on a glass substrate have been suggested as polarizing devices used for light valves in liquid crystal projectors. A line-to-spacing (L/S) ratio, where a grid width is defined as L and a space between grids is defined as S, is an important parameter to determine the optical property of the polarizing devices. For instance, a high optical property is obtained by making the L/S ratio small, in other words, increasing the space between the grids and narrowing the width of the lines.
The aforementioned grid patterns are formed by patterning, for instance, Al with dry etching. The optical property of the polarizing devices is therefore affected by a state of Al during dry etching. However, controlling the structure of a pattern in dry etching is difficult when forming a grid pattern (polarizing device unit) with a high aspect ratio as well as with a small L/S ratio. In order to prevent the side etching derived from the above problem, one technique utilizes tungsten (W) that has a higher selection ratio with respect to Al as a mask (refer to JP-A-5-136103 for an example).
However, using a tungsten mask alone does not resolve the difficulties in controlling the endpoint during dry etching (prevention of side etching), and the grid pattern with a high aspect ratio structure may not be formed in a high precision. Moreover, in the technique described above, a TiN layer is used as an undercoat layer for the Al layer. Since the optical transparency of the TiN layer is low, the TiN layer being formed on the surface of the glass substrate, a desired optical property may not be obtained when applying the above technique to the manufacturing of the polarizing device. Therefore, a new technique alternative to the above etching technique has been desired.